CAB-S-S-25G-xM-BCC | Arista Compatible SFP28 To SFP28 Copper Direct-Attach 25GBASE-CR1 Cable | 1 to 5M

Q: Will this work in place of the Arista CAB-S-S-25G-1M?
A: Yes. This cable matches the Arista CAB-S-S-25G-1M electrical and mechanical specifications, conforming to IEEE 802.3by 25GBASE-CR1 and SFP28 MSA standards. It is plug-and-play compatible with Arista switches and any equipment with SFP28 ports supporting 25GBASE-CR1. The cable operates at 25 Gb/s data rate over passive copper twinax.

Q: Which Arista platforms support this cable?
A: This cable works in any Arista switch with SFP28 ports that comply with IEEE 802.3by and SFP28 MSA standards. This includes modular spine and leaf platforms with 25G connectivity. Consult Arista's transceiver and cable compatibility guide for your specific model, or verify that your platform supports 25GBASE-CR1 passive DAC cables.

Q: Do different cable lengths require different FEC settings on my switch ports?
A: Yes. The 1M, 1.5M, and 2M lengths do not require FEC and can operate at lower latency. The 2.5M and 3M lengths require BASE-R FEC (also called FC-FEC) enabled on both host ports. The 5M length requires RS-FEC on both ends. Refer to IEEE 802.3by cable classifications CA-N, CA-S, and CA-L, which define loss budgets and corresponding FEC minimums. Your switch configuration must match the cable length FEC requirement for reliable link operation.

Q: Can I use this cable at 10G instead of 25G?
A: Yes. Arista 25G twinax copper cables support dual-rate operation at both 25G and 10G speeds. Configure your switch port for 10G, and the cable will establish a 10GBASE-CR link. This allows you to reuse the same cable inventory during network migrations from 10G to 25G infrastructure without replacing physical cabling.

Q: What is the power consumption per connector, and how does passive copper compare to fiber or AOC?
A: Passive copper DAC cables consume minimal power, typically under 0.6W per end, as they rely solely on the host transceiver to drive the electrical signal without active components. This is significantly lower than fiber optic transceivers or Active Optical Cables, which require lasers and receivers. For short intra-rack or adjacent-rack links, passive copper offers the lowest cost, power, and latency profile, making it the preferred choice for data center top-of-rack and storage fabric applications.